Comparison of ePlex Respiratory Pathogen Panel with Laboratory-Developed Real-Time PCR Assays for Detection of Respiratory Pathogens

Abstract

Infections of the respiratory tract can be caused by a diversity of pathogens, both viral and bacterial. Rapid microbiological diagnosis ensures appropriate antimicrobial therapy as well as effective implementation of isolation precautions. The ePlex respiratory pathogen panel (RP panel) is a novel molecular biology-based assay, developed by GenMark Diagnostics, Inc. (Carlsbad, CA), to be performed within a single cartridge for the diagnosis of 25 respiratory pathogens (viral and bacterial). The objective of this study was to compare the performance of the RP panel with those of laboratory-developed real-time PCR assays, using a variety of previously collected clinical respiratory specimens. A total of 343 clinical specimens as well as 29 external quality assessment (EQA) specimens and 2 different Middle East respiratory syndrome coronavirus isolates have been assessed in this study. The RP panel showed an agreement of 97.4% with the real-time PCR assay regarding 464 pathogens found in the clinical specimens. All pathogens present in clinical samples and EQA samples with a threshold cycle (C_T ) value of <30 were detected correctly using the RP panel. The RP panel detected 17 additional pathogens, 7 of which could be confirmed by discrepant testing. In conclusion, this study shows excellent performance of the RP panel in comparison to real-time PCR assays for the detection of respiratory pathogens. The ePlex system provided a large amount of useful diagnostic data within a short time frame, with minimal hands-on time, and can therefore potentially be used for rapid diagnostic sample-to-answer testing, in either a laboratory or a decentralized setting.

Keywords: influenza; point-of-care testing; rapid diagnostics; respiratory pathogens; sample-to-answer.

FIG 1

ePlex system (A) and the corresponding cartridge of the ePlex respiratory pathogen panel (B).

FIG 2

Principle of the eSensor detection technology. Amplified sequences of the targeted pathogens are detected electrochemically using a complementary pathogen-specific signal probe tagged with ferrocene, a reducing agent. The hybridized molecule is then exposed to another sequence-specific probe that is bound to a solid phase, which is a gold electrode (A). Upon binding of the two molecules, the ferrocene comes in close proximity to the gold electrode, where an electron transfer that can be measured using GenMark's eSensor technology on the ePlex system can occur (B).

FIG 3

Pathogen concordance by C_T value.